Mayor defends decision to re-open CBD

Mr Lester defended the council's decision to re-open the CBD on Tuesday, saying it was made with the best advice staff had from engineers at the time.

Prime Minister John Key and senior government ministers had supported that, he said.

"They're all confident that we are making the right decisions."

Putting a cordon around the entire CBD would affect the 99 percent of buildings that had made it through the earthquake without major problems, he said.

He would meet with engineers later this afternoon to get the latest information.

The Reading Cinema parking building was a priority, he said.

"Within the next 24 hours they will have worked up a plan. There will be a structural repair which will secure the building in the short term. That will allow us to reduce the cordon, and give us time to understand the long-term future of the building."

Other buildings could be in the firing line depending on engineering assessments.

"We want to make sure we weed out those buildings with structural weaknesses in the city - we don't want them in our city in the future, we will make sure where necessary they come down."

As well as the three unsafe buildings, another 16 were on a list of buildings of concern, Mr Lester said.

That number could grow as detailed assessments were done.

GNS seismologist Matt Gerstenberger told the news conference the aftershock sequence in Wellington and elsewhere seemed to be following a fairly normal pattern.

"The number of events are decreasing in time, which means the the probability of further events is also decreasing with time."

The chances of another intense shake were as high as 80 percent close to the site of the original quake, but that decreased to a five to 10 percent probability for Wellington, he said.

Offices and schools take precautions

Housing New Zealand staff in Wellington were told to go home today while more detailed assessments of their central-city building took place.

The owner of the Boulcott Street building arranged for an engineers' inspection following Monday's earthquake. That report came back saying the building was structurally sound.

However, staff noticed a change to the floor angle on Level Nine, which Housing New Zealand reassessed today.

Housing New Zealand spokesperson Bryony Hilless said staff had been asked to leave so engineers could carry out a further inspection.

It was unclear whether occupants on other floors had also left.

Wellington Girls College also sent junior students home early because of concerns about stairways. The college said its buildings were safe, but engineers asked it to close two stairwells so they could check cracks.

The school will remain open for exams, but will be closed to juniors on Monday.

Parts of the Queensgate shopping centre in Lower Hutt would also remain off limits, because of damage to its car park.

The mall's property managers said one of the car park buildings had structural damage, which could get worse in a big aftershock. The car park was not in danger of collapse, and engineers had found no structural damage to the retail area.

And BNZ said it still could not put on a date on when workers in its building in Harbour Quays would be allowed back in following the quake.